The invention relates to a method for lubricating a tool and a workpiece at cutting and forming, especially fine blanking of a workpiece with a thickness of 5 mm or more and with complex part geometry from a flat strip, wherein the flat strip, wetted on the surface with a lubricating oil film of sufficient thickness at closing, is clamped between an upper part consisting of a shearing punch, a pressure pad for the shearing punch, a V-shaped projection positioned on the pressure pad and an ejector and a lower part consisting of cutting die, ejector and a inner form punch, and the lubricating oil by the pressure pad, the shearing punch, the ejector, the cutting die, the ejector and the inner form punch is pressed out and forced into chamfers at the pressure pad and the ejectors forming lubrication bore reliefs in which it is temporarily stocked up.
The invention further relates to a method for lubricating a tool and a workpiece at cutting and forming, especially fine blanking of a workpiece with a thickness of 5 mm or more and with complex part geometry from a flat strip, wherein the flat strip, wetted on the surface with a lubricating oil film of sufficient thickness at closing, is clamped between an upper part consisting of a shearing punch, a pressure pad for the shearing punch, a V-shaped projection positioned on the pressure pad and an ejector and a lower part consisting of cutting die, ejector and a inner form punch, wherein the effective gaps between shearing punch and pressure pad, cutting die and ejector as well as shearing punch and inner form punch are supplied with cutting oil.
The invention further relates to a method for lubricating a tool and a workpiece at cutting and forming, especially fine blanking of a workpiece with a thickness of 5 mm or more and with complex part geometry from a flat strip with a tool consisting of two parts with at least one shearing punch, one pressure pad for the shearing punch, one positioned on the pressure pad V-shaped projection, one ejector, one cutting die, one ejector and an inner form punch, wherein the flat strip, wetted on both sides with a lubricating oil film of sufficient thickness, is clamped between pressure pad and cutting die and the lubricating oil on the upper side of the workpiece is collected in chamfers positioned at the pressure pad and the ejector and on the bottom side in chamfers at the cutting die and the ejector forming lubrication bore reliefs, wherein effective gaps between shearing punch and pressure pad, cutting die and ejector and shearing punch and inner form punch are provided to supply the cutting oil.
The invention further relates to a method for lubricating a tool and a workpiece at cutting and forming, especially fine blanking of a workpiece with a thickness of 5 mm or more and with complex part geometry from a flat strip, with a tool consisting of two parts with at least one shearing punch, one pressure pad for the shearing punch, one positioned on the pressure pad V-shaped projection, one ejector, one cutting die, one ejector and an inner form punch, wherein the flat strip, wetted on both sides with a lubricating oil film of sufficient thickness, is clamped between pressure pad and cutting die and effective gaps between shearing punch and pressure pad, cutting die and ejector and shearing punch and inner form punch are provided to supply the cutting oil.
It is known that fine blanking, because of the high wear associated therewith, cannot be realized without lubricating oil. Fine blanking without lubricating oil, especially in case of thicker parts, already after a few strokes, leads to bonding between the shearing punch and the material of the workpieces. In addition, in the case of thinner parts, bluntness of the tool occurs rapidly.
As known from “Umformen and Feinschneiden—Handbuch für Verfahren, Stahlwerkstoffe, Teilegestaltung” (R. A. Schmidt, Carl-Hanser-Verlag 2007, Munich, Vienna, p. 241-243) the wear stress of the shearing punch, the cutting die, the V-shaped projection and the inner form punch in the fine blanking tool reaches a serious degree, and the tendency towards cold bondings between punch and workpiece grows significantly, especially in the case of a workpiece thickness of more than 10 mm.
To oppose wear and cold bonding, this state of the art proposes to provide the workpiece or the strip, on the upper and lower sides thereof, with an oil film of sufficient thickness. The lubricated strip is pushed into the open tool and clamped between the upper and the lower parts of the tool when it closes. The oil on the upper and lower sides of the strip, on the one hand, is pressed out by the pressure pad, the shearing punch and the ejector of the cutting tool and, on the other hand, by the cutting plate, the ejector and the inner form punch and forced into lubrication bore reliefs, on the upper side of the strip formed by chamfers at the pressure pad and the ejector and on the bottom side by a chamfer at the ejector.
Despite all theses measures, it remained heretofore a problem to provide a sufficient quantity of lubricating oil to the forming zone, so as to allow fine blanking of parts thicker than 10 mm and with complex part geometry.
From DE 1 752 239 it is further known to apply a die-plate of porous hard metal. Lubricating material deposits in the pores of the die-plate contributes to the lubricating film not breaking off during cutting. However, this known solution cannot insure that the lubricant can reach the forming zone.
At this state of the art, it is an object of the invention to further develop a method and a device for lubricating a tool and a workpiece at cutting and forming, especially at fine blanking of a workpiece, so that fine blanking of thicker parts is reproducible, controlled process secure, with high quality and at the same time, extended edge life of the tools is achieved by lubricating the active surfaces up to the forming zone without the provided lubricating film breaking off.